The invention relates to an apparatus for the fibre-sorting or fibre-selection of a fibre bundle comprising textile fibres, especially for combing.
In a known apparatus, fibre material is supplied by means of a supply device to a fibre-sorting device, especially to a combing device, in which clamping devices are provided, which clamp the fibre bundle at a distance from its free end and mechanical means are present which generate a combing action from the clamping site to the free end of the fibre bundle in order to loosen and remove non-clamped constituents, such as, for example, short fibres, neps, dust and the like from the free end.
In practice, combing machines are used to free cotton fibres or woollen fibres of natural impurities contained therein and to parallelise the fibres of the fibre sliver. For that purpose, a previously prepared fibre bundle is clamped between the jaws of the nipper arrangement so that a certain sub-length of the fibres, known as the “fibre tuft”, projects at the front of the jaws. By means of the combing segments of the rotating combing roller, which segments are filled with needle clothing or toothed clothing, this fibre tuft is combed and thus cleaned. The take-off device usually consists of two counter-rotating rollers, which grip the combed fibre bundle and carry it onwards. The known cotton-combing process is a discontinuous process. During a nipping operation, all assemblies and their drive means and gears are accelerated, decelerated and in some cases reversed again. High nip rates result in high acceleration. Particularly as a result of the kinematics of the nippers, the gear for the nipper movement and the gear for the pilgrim-step movement of the detaching rollers, high acceleration forces come into effect. The forces and stresses that arise increase as the nip rates increase. The known flat combing machine has reached a performance limit with its nip rates, which prevents productivity from being increased. Furthermore, the discontinuous mode of operation causes vibration in the entire machine, which generates dynamic alternating stresses.
EP 1 586 682 A discloses a combing machine in which, for example, eight combing heads operate simultaneously one next to the other. The drive of those combing heads is effected by means of a lateral drive means arranged next to the combing heads having a gear unit, which is in driving connection by way of longitudinal shafts with the individual elements of the combing heads. The fibre slivers formed at the individual combing heads are transferred, one next to the other on a conveyor table, to a subsequent drafting system in which they are drafted and then combined to form a common combing machine sliver. The fibre sliver produced in the drafting system is then deposited in a can by means of a funnel wheel (coiler plate). The plurality of combing heads of the combing machine each have a feed device, a pivotally mounted, fixed-position nipper assembly, a rotatably mounted circular comb having a comb segment for combing out the fibre tuft supplied by the nipper assembly, a top comb and a fixed-position detaching device for detaching the combed-out fibre tuft from the nipper assembly. The nipper assembly comprises a lower nipper, which co-operates with an upper nipper plate. The upper nipper plate is here pivotally mounted on the lower nipper by way of a pivot axis. The lower nipper and the upper nipper are formed with complementary profiles at their front end region, via which, when the nipper assembly is closed, they clamp the lap supplied via a feed cylinder. The fibre tuft FB protruding in this clamped position from the nipper assembly is combed by a comb segment of a circular comb. The circular comb arranged beneath the nipper assembly is secured, without relative rotation, on a circular comb shaft, which is connected via the drive connection to the gear mechanism. The drive of the gear mechanism is effected by a main motor. The nipper assembly is pivotally mounted on the axis of the circular comb shaft via a pivot arm. The free end of the pivot arm is fixedly secured to the frame of the lower nipper. In its rear region, the lower nipper has a pivot axis, on which a lever is rotatably mounted. This lever is rotatably secured via an axle to a crank disc. The axle of the crank disc is in connection via a drive connection with a drive motor. The motor is in connection with the central control unit via the control line. In order to co-ordinate the electromotive drives with the drive of the circular comb, a sensor is provided, which is in connection with the control unit via the line. The function of this sensor is to detect the particular angular position of the shaft of the circular comb and relay this to the control unit. It is thus possible to output appropriate control pulses to the relevant motors via the control unit, so that, on the one hand, the combing segment combs out the fibre tuft FB at a defined point in time and, on the other hand, the rotary movement of the detaching roller pair respectively the transport roller pair is co-ordinated with the nipper movement. In this way, a mechanical combing of the fibre material is effected. Disadvantages of that combing machine are especially the large amount of equipment required and the low hourly production rate. There are eight individual combing heads which have in total eight feed devices, eight fixed-position nipper assemblies, eight circular combs with comb segments, eight top combs and eight detaching devices. A particular problem is the discontinuous mode of operation of the combing heads. Additional disadvantages result from large mass accelerations and reversing movements, with the result that high operating speeds are not possible. Finally, the considerable amount of machine vibration results in irregularities in the deposition of the combed sliver. Moreover, the ecartement, that is to say the distance between the nipper lip of the lower nipper plate and the clamping point of the detaching cylinder, is structurally and spatially limited. The rotational speed of the circular comb is co-ordinated with the slow (discontinuous) combing process, in particular the discontinuous and slow movements of the nippers, and is limited by this. In addition, the profiled end regions of the upper and lower nipper suffice for the feed respectively positioning at slow speed of the fibre tuft to be combed out. High-speed combing with this apparatus is not possible.